vkset(par)
struct vkpar *par;
vkbeg
vkstat (stat)
struct vkinfo *stat;
The voice key is controlled using the routines vkset to initialize parameters, vkbeg to start the operation, and vkstat to obtain statistics after the operation has completed.
vkset
vkset
must be called once before calling either of the other voice key
routines. Once it has been called it is not necessary to call it
again unless some of the parameters it sets must be changed.
vkset
is called with the argument
par,
a pointer to a structure defined in vkey_u.h:
struct vkpar {
unsigned stoptime;
unsigned checktime;
int channel;
int l_thresh;
int h_thresh;
int l_rundef;
int h_rundef;
unsigned *begspeech;
unsigned *endspeech;
int *l_savbuf;
int *h_savbuf;
int sbufsize;
};
par->stoptime
specifies the clock time at which to stop monitoring the audio signal
if the beginning of speech has not yet been detected. If the
beginning of speech has been detected, the voice key will continue
operating for a specified time after the last speech sample is found.
That time is given in
par->checktime.
The voice key uses the programmable clock to time these intervals.
par->channel is the A/D channel to which the low energy measure from the voice key is connected. The high energy measure is input to par->channel+1.
The speech detection algorithm operates on the low and high energy measures independently. For the low energy measure, if the sample is greater than or equal to par->l_thresh it is classified as a hit. The onset of speech occures at the first sample in a consecutive run of par->l_rundef of more hits. The same algorithm is used for high energy using the parameters par->h_thresh and par->h_rundef.
If speech is detected in either or both energy measures, the earlier onset time and the later offset time are returned in par->begspeech and par->endspeech. If speech is not detected in either measure par->begspeech returns the value VK_NOBEG.
Low and high energy samples (hits and non-hits) are saved in buffers pointed to by par->l_savbuf and h_savbuf. The buffers must each be of size par->sbufsize to save that many samples each. If par->l_savbuf and par->h_savbuf are NULL samples are not saved.
vkbeg
After
vkset
has been called and the clock started (if it is not already running)
the voice key is started by invoking
vkbeg.
It will continue to run either until the end of speech, or until
par->stoptime
is reached if no speech is found. The calling program can determine
when the voice key has finished by checking
*par->endspeech.
If the value is equal to VK_NOEND the voice key is still operating.
vkstat
When the voice key has stopped, measures other than the beginning and
ending speech times or the raw high and low energy samples are
obtained by calling
vkstat.
The argument
stat
points to another structure defined in vkey_u.h;
struct vkinfo {
int l_bwind;
int h_bwind;
int l_ewind;
int h_ewind;
int l_peak;
int h_peak;
int l_avg;
int h_avg;
}
The window numbers of speech onsets for low and high energies are
given by
stat->l_bwind
and
stat->h_wind
(windows are numbered beginning with 0). The window numbers of speech
offsets are given by
stat->l_ewind
and
stat->h_ewind. stat->l_peak
and
stat->h_peak
are the maximum low and high energies during speech;
stat->l_avg
and
stat->h_avg
are the average low and high energies during speech. Before relying
on the temporal precision of the windows, it is suggested that the
100Hz voice key clock be calibrated, as it has been known to drift.
/* test voice key */
#include <vkey_u.h>
#include <clock_u.h>
#include <stdio_p.h>
#define LRUNDEF 4
#define HRUNDEF 4
#DEFINE LTHRESH 17
#define HTHRESH 8
#define CHAN 1
#define CHECK 100
#define STOP 1000
#define BUFSZ 1000
static unsigned vbeg, vend;
int lbuf[BUFSZ];
int hbuf[BUFSZ];
main()
{
struct vkpar v;
struct vkinfo s;
v.stoptime = STOP;
v.checktime = CHECK;
v.channel = CHAN;
v.l_thresh = LTHRESH;
v.h_thresh = HTHRESH;
v.l_rundef = LRUNDEF;
v.h_rundef = HRUNDEF;
v.begspeech = &vbeg;
v.endspeech = &vend;
v.l_savbuf = lbuf;
v.h_savbuf = hbuf;
v.sbufsize = BUFSZ;
if (vkset(&v) == -1)
errexit(1,"vkset error0");
ckreset(CKR_1MS);
ckstart;
if(vkbeg == -1)
errexit(2,"vkbeg error0");
while(vend == VK_NOEND)
;
if(vkstat(&s) == -1)
errexit(3,"vkstat error0");
printf("begtime = %uendtime = %u0",vbeg,vend);
printf("lbeg = %dlend = %dlpeak = %dlavg = %d0",
s.l_bwind,
s.l_ewind,
s.l_peak,
s.l_avg);
printf("hbeg = %dhend = %dhpeak = %dhavg = %d0",
s.h_bwind,
s.h_ewind,
s.h_peak,
s.h_avg);
}